A) Field of the Invention
The present invention relates to a semiconductor light emitting device, and more particularly to a light emitting device having a metal reflective layer.
B) Description of the Related Art
In order to develop a higher illuminance light emitting device such as a light emitting diode (LED), it is very important to improve an optical output efficiency of light to be guided to an external of the device. For example, in a structure that a semiconductor lamination structure made of aluminum gallium indium phosphorus (AlGaInP) is stacked on a gallium arsenic (GaAs) substrate, light radiated toward the substrate among light emitted in an active layer is absorbed in the GaAs substrate so that a high optical output efficiency cannot be obtained. It is therefore an important approach to a high luminance no to make the light propagating toward the substrate among light omnidirectionally emitted be absorbed in the substrate, but to guide the light to an external of the device.
As an approach to improving the optical output efficiency, there has been proposed a bonding type structure that after a semiconductor lamination structure is epitaxially grown on a temporary substrate, the temporary substrate is removed, and a metal reflective layer for reflecting emitted light is formed and bonded to a conductive substrate such as a metal substrate.
Semiconductor light emitting devices of this type are proposed, for example, in JP-A-2001-189490, JP-A-2001-44491 and JP-A-2002-217450.